1. Field of the Invention
The invention relates generally to electrical power switch apparatuses, and more particularly, to an actuator assembly thereof that can be calibrated.
2. Background Information
Several types of electrical power switch apparatuses, such as, circuit breakers, transfer switches, and disconnect switches are known. Such apparatuses include an operating mechanism, typically actuated by an actuator assembly, for opening the switch. For example, an actuator assembly used in conjunction with a circuit breaker interacts with the operating mechanism to separate the circuit breaker contacts upon occurrence of an overcurrent condition within a protected electrical distribution system.
Actuator assemblies, such as utilized in conjunction with circuit breakers, are generally known. For certain known circuit breakers, the actuator assembly receives a pulse electrical signal from an electronic trip unit to actuate the operating mechanism. The signal is usually a low power signal due to the limited power available from the electronic trip unit. Therefore, it is important that the actuator assembly consistently be actuated by the low power signal to insure proper operation of the actuator assembly and the circuit breaker. However, this becomes increasingly difficult in view of manufacturing variations inherent in the manufacturing processes of the actuator assembly components. Particularly because slight manufacturing variations, such as, for example, surface roughness of the holding magnet and armature, directly affect the magnitude of the low power signal needed to actuate the actuator assembly.
U.S. Pat. No. 5,453,724 sets forth an actuator assembly. This assembly employs a holding magnet to retain an armature against the propelling bias of a compression spring. A coil assembly circumferentially disposed about the armature receives a pulse electrical signal which bucks the magnetic force provided by the holding magnet and releases the armature.
There is a need, therefore, for an electrical power switch apparatus having an improved actuator assembly.
There is also a need for an electrical power switch apparatus having an actuator assembly that is consistently actuated by a pulse electrical signal.
There is a further need for an electrical power switch apparatus having an actuator assembly that accounts for manufacturing variations of the actuator assembly components to assure consistent actuation of the actuator assembly.